up3

server/entity/stationary.go

@@ -0,0 +1,72 @@
+package entity
+
+import (
+	"github.com/df-mc/dragonfly/server/world"
+	"math"
+	"time"
+)
+
+// StationaryBehaviourConfig holds settings that influence the way
+// StationaryBehaviour operates. StationaryBehaviourConfig.New() may be called
+// to create a new behaviour with this config.
+type StationaryBehaviourConfig struct {
+	// ExistenceDuration is the duration that an entity with this behaviour
+	// should last. Once this time expires, the entity is closed. If
+	// ExistenceDuration is 0, the entity will never expire automatically.
+	ExistenceDuration time.Duration
+	// SpawnSounds is a slice of sounds to be played upon the spawning of the
+	// entity.
+	SpawnSounds []world.Sound
+	// Tick is a function called every world tick. It may be used to implement
+	// additional behaviour for stationary entities.
+	Tick func(e *Ent, tx *world.Tx)
+}
+
+func (conf StationaryBehaviourConfig) Apply(data *world.EntityData) {
+	data.Data = conf.New()
+}
+
+// New creates a StationaryBehaviour using the settings provided in conf.
+func (conf StationaryBehaviourConfig) New() *StationaryBehaviour {
+	if conf.ExistenceDuration == 0 {
+		conf.ExistenceDuration = math.MaxInt64
+	}
+	return &StationaryBehaviour{conf: conf}
+}
+
+// StationaryBehaviour implements the behaviour of an entity that is unable to
+// move, such as a text entity or an area effect cloud. Applying velocity to
+// such entities will not move them.
+type StationaryBehaviour struct {
+	conf  StationaryBehaviourConfig
+	close bool
+}
+
+// Tick checks if the entity should be closed and runs whatever additional
+// behaviour the entity might require.
+func (s *StationaryBehaviour) Tick(e *Ent, tx *world.Tx) *Movement {
+	if s.close {
+		_ = e.Close()
+		return nil
+	}
+
+	if e.Age() == 0 {
+		for _, ss := range s.conf.SpawnSounds {
+			tx.PlaySound(e.Position(), ss)
+		}
+	}
+	if s.conf.Tick != nil {
+		s.conf.Tick(e, tx)
+	}
+
+	if e.Age() > s.conf.ExistenceDuration {
+		s.close = true
+	}
+	// Stationary entities never move. Always return nil here.
+	return nil
+}
+
+// Immobile always returns true.
+func (s *StationaryBehaviour) Immobile() bool {
+	return true
+}